This question is quite unimportant, so feel free to close if you think it is inappropriate.

I've been thinking about how mathematicians come up with names for the ideas/objects they study, and how that differs from the practices of people in other fields.

It seems that almost always we do one of two things: 1) we pick a name that describes some feature of the object (sometimes not very well, e.g. flat modules, sets of second category), or 2) we name it after a person (who may or may not have studied that object).

Very rarely we name something after a place. (This is much more common in other fields.)
I can think of only 3 examples:

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+1, I think this is at least a little amusing. I must admit, I don't understand why this question has been received poorly (as indicated by the number of votes on SNd's comment, and the number of upvotes on the question itself) when other "empty questions," such as the one about jokes, get over 30 positive votes. What am I missing?
–
Eric NaslundMay 11 '11 at 19:54

11

A matter of timing, I suspect. The crowd is just not in the mood.
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Tom GoodwillieMay 11 '11 at 21:05

9

-1. I voted this down because I don't see the value in the question being open (just go to Emmanuel's blog post if you're interested in this). The question is just taking up valuable real estate on the front page as it gets continually bumped by what are generally low quality answers. (and even the OP claims the question is unimportant!)
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Peter McNamaraMay 12 '11 at 5:01

It was at this point that the terminology of quasigroup theory underwent a
historic change. It became apparent that it was necessary to distinguish between
two classes of quasigroups: those with and those without an identity element.
A new name was needed to designate the system with identity. This occurred
around 1942, among people of Albert’s circle in Chicago, who coined the word
“loop” after the Chicago Loop. For Chicago locals, the term “Loop” designated
the main business area and the elevated train that literally made a loop around
this part of the city.

The French Railroad metric: if $(X,d)$ is a metric space, and $p \in X$, define $d_R(x,y) = 0$ if $x = y$ and $d_R(x,y) = d(x,p) + d(y,p)$ otherwise. Apparently named so because almost every train in France goes trough Paris.

Why is this the Washington DC metric? (Washington is not nearly as central in the US as London is in the UK or Paris is in France...)
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Michael LugoMay 11 '11 at 22:26

1

@Michael Probably because of the layout of the DC Metro--to move between two outer locations (say Shady Grove and Vienna/Fairfax), one often has to travel to the center of the District along the way.
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Justin LanierMay 12 '11 at 5:50

"The Roman surface (so called because Jakob Steiner was in Rome when he thought of it) is a self-intersecting mapping of the real projective plane into three-dimensional space, with an unusually high degree of symmetry."

Aarhus integral, Polish notation, English/French notation (or something like that - it refers to different ways to draw Ferrers diagrams - or was it English/Italian?), Tower of Hanoi, Russian constructivism (Russian school of intuitionism).

Perhaps a stretch, but in mathematical finance it is traditional to name option styles after places. American and European are the most common, but http://en.wikipedia.org/wiki/Option_style also lists Bermudan, Canary, Asian, Russian, Israeli, and Parisian.

There's a Four Russians algorithm in computer science. I don't remember what the algorithm did or who the four Russians were, but the description "named after the cardinality and nationality of its inventors" stuck in my mind. I think that description is from the first edition of Principles of Compiler Design (aka the Green Dragon Book) by Aho and Ullman. (Googling finds some descriptions of the algorithm).